Before going into any build, determine what it'll be used for, i.e. drag racing, short course, street bombing, etc. Then check availability of parts needed and what's going to need done to make them work, i.e. tires, brakes, wheels, shocks?, welding, etc. Having the wrong tires on a drag bike or not being able to stop within a reasonable distance because you couldn't weld on the right caliper bracket defeats the purpose. Building a drag racing engine and using it on a MX course, again, defeats the purpose.
There is a science to engine building but trial and error and implementing your own ideas can often make the difference. All these guys seem to use big terms and the one who uses more of them sells more parts. A lot of the 50 point list he talks about in his video are just things that need to (or should be) done when building a head anyway.
I noticed in his video he talks a lot about "Flow" and how his heads flow better. Well that's all fine and dandy but if your intake manifold doesn't match the intake port on your head, it becomes a bottleneck. I have one of those 24/28mm flat slide intakes and I noticed it tapers to the stock port size, If left alone, it will restrict airflow and defeat everything that went into the head.
What I do is, determine what I want to build it for, choose a cam that is suitable for what my intended use is, figure my target RPM range, compression ratio, valve size and spring pressure and go from there. Bigger isn't always better, matching the right components will outperform the bigger is better mentality. Take polishing ports for instance, one would think that the smoother the better/faster the air flows thus making more power. I've seen stepped ports outperform polished ports of the same size on race car engines, due to the design the turbulence actually mixed the fuel/air better going into the combustion chamber.
The one thing I noticed on all of the Pauls Karts heads is the pitting in the welded portion of the combustion camber. While it is hard to weld cast aluminum, those pits will cause carbon "Hot spots" and can cause pre-ignition which can cause catastrophic failure. Also take into consideration that race engines are rebuilt/replaced on a regular basis and they aren't intended to be built for reliability. 60lb. spring pressure may work on an engine that's going to be torn down after every fifth race but don't expect it to run down to the corner store every day for a month without ruining your cam. Speaking of cams, invest in some cam break-in lube. Breaking in the cam properly is probably most important thing one can do to prevent premature lobe failure!.